Facebook login api get email

To get the email address of a user who has logged in using the Facebook Login API, you need to make a request to the /me endpoint and include the email permission in your authorization request.

Here are the steps:

1. Register your app: First, you need to register your app on Facebook Developer Platform. Go to Facebook for Developers and create a new app.
2. Get an App ID and App Secret: Once you've created your app, you'll get an App ID and App Secret. You'll need these to authenticate your app.
3. Add the email permission: In the Facebook Developer Platform, go to your app's settings and add the email permission to the list of permissions your app is allowed to request.
4. Make an authorization request: When a user logs in to your app using the Facebook Login API, you'll need to make an authorization request to Facebook. You can do this by sending a GET request to https://www.facebook.com/v3.3/dialog/oauth?client_id=YOUR_APP_ID&redirect_uri=YOUR_REDIRECT_URI&scope=email.
5. Get the access token: After the user grants permission, Facebook will redirect the user back to your app with an authorization code. You can then exchange this code for an access token by sending a POST request to https://graph.facebook.com/v3.3/oauth/access_token?client_id=YOUR_APP_ID&redirect_uri=YOUR_REDIRECT_URI&client_secret=YOUR_APP_SECRET&code=AUTHORIZATION_CODE.
6. Make a request to the /me endpoint: Once you have the access token, you can use it to make a request to the /me endpoint to get the user's profile information, including their email address. You can do this by sending a GET request to https://graph.facebook.com/v3.3/me?access_token=ACCESS_TOKEN.

Here's an example of what the request might look like in JavaScript:

const facebookApiUrl = 'https://graph.facebook.com/v3.3';
const appId = 'YOUR_APP_ID';
const appSecret = 'YOUR_APP_SECRET';
const redirectUri = 'YOUR_REDIRECT_URI';
const authorizationCode = 'AUTHORIZATION_CODE';

// Exchange authorization code for access token
fetch(`${facebookApiUrl}/oauth/access_token?client_id=${appId}&redirect_uri=${redirectUri}&client_secret=${appSecret}&code=${authorizationCode}`)
 .then(response => response.json())
 .then(data => {
    const accessToken = data.access_token;

    // Make request to /me endpoint to get user's profile information
    fetch(`${facebookApiUrl}/me?access_token=${accessToken}`)
     .then(response => response.json())
     .then(data => {
        const email = data.email;
        console.log(email);
      });
  });

Note that the email permission is only available for users who have granted permission for your app to access their email address. If a user has not granted this permission, you will not be able to get their email address.